Seminar & Colloquium
[세미나: 11월 11일(금), 오전 10시] Prof. Paloma Fernández Sánchez, Complutense University of Madrid
Title
Characterization and luminescence properties of RE (Er, Tb, Eu) and Li codoped ZnO nanostructures
Speaker
Professor. Paloma Fernandez Sanchez, Department of Materials Physics, Complutense University of Madrid
Biography
I studied Physics at University Complutense, where I also received my PhD in 1989.
I joined the Department of Materials Physics (UCM) in 1986 as an assistant professor and since 2007 I am a Full Professor in Materials Science and Metallurgical Engineering.
My main line of research is the study of defects in semiconductors and oxides, where I have published circa 160 articles. My current h index is 27, with i10 of 75, and ca. 3000 cites.
As special academic positions, at my own University, I have been Deputy Director of Department of Materials Physics (1993-2010) and I am currently, since 2011, Responsible for the Physics and Chemistry Section in the Master for Secondary and High School Teachers.
I have been President of the Spanish Materials Society (2007-2016). Within the Federation of European Materials Societies (FEMS) I have been member of the Executive Committee (2014-2016) Vice-president (2016-2017) and President (2018-2019).
I am an active member of COSCE (Federation of Spanish Scientific Societies) and belong to the permanent boards of the projects focused on STEM and Science for early aged scholars.
I received the Research Award from Universidad de La Habana and the Outreach and Education in Materials Science from SOCIEMAT
| Date | Friday, November 11th, 2022
| Time | 10:00 ~
| Venue | 33동 125호 (WCU 다목적실)
[Abstract]
ZnO nanostructures have been extensively investigated during the last years due to their application in different optoelectronic devices. The wide direct bandgap (3.37 eV at room temperature), high exciton binding energy (60 meV) and high refraction index (n=2.45) make this material a good candidate to fabricate the next generation optical nanodevices. In this regard, doping ZnO nanostructures with rare earth ions is particularly significant since the optical properties of the nanostructures can be modified. Among these ions, Er3+ is interesting since it shows an intense intraionic transition at 0.8 eV (1.54 µm) which corresponds to minimal loss wavelength in optical communications. Furthermore, codoping semiconductor nanostructures is an efficient method to increase the intensity of this emission. In particular, Li+ ions have been shown? to be a good candidate as activator since they slightly alter Er3+
symmetry which leads to a variation of probabilities of the intraionic transitions [1].
In this work, micro- and nanostructures of ZnO codoped with Er and Li and Tb and Li respectively, have been grown by a catalyst free vapor-solid method under constant N2 flux. Nanowires and nanobelts with lengths of several microns, and thicknesses of a few hundreds of nanometers have been obtained [Fig 1(a)]. The amount of Er3+ Tb3+ incorporated into the structures has been assessed by Energy Dispersive X-ray Spectroscopy (EDX) and ranges between 2 and 6 %wt. Luminescent emission of the samples has been studied by cathodo- and photoluminescence (CL and PL). In the case of Er doped samples, as it is shown in figure 1(b), the relative intensity of the 0.8 eV (1.54 µm) emission band is higher in the codoped samples than in the samples where only Er3+ is used as dopant. The light guiding properties of the nanostructures obtained have been studied by µPL. Figure 1c shows that the luminescence is guided along the codoped nanostructures. Spectra recorded at the exit point show that free excitons emission of ZnO is reabsorbed by the material in its path along the nanobelt while bound excitons and deep level emission bands are still present. Finally, optical resonant modes have also been observed in the nanostructures which gives rise to the possibility of using them in a wide variety of optical nanodevices.
| Host | 장호원 교수 (880-7092)